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The influence of light on mood and emotion

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Abstract

In the 7 th century William Shakespeare wrote "A sad tale's best for winter". However, he was not the first who understood the power of light on our psyche. 2000 years ago Hippocrates, the father of modern medicine, already acknowledged that the absence of light, particularly in winter, can produce diseases. Since then, the impact of light on mood and the use of bright light as a treatment-option for affective disorders have been studied extensively by scientists (for a review see Terman & Terman 2005). Light is the major zeitgeber for human circadian rhythms, much more powerful than social zeitgebers eg. work or school schedules (Challet 2007). Non-visual effects of light include hormone regulation, the synchronization of the circadian system, the regulation of body temperature, but also the regulation of cognition and alertness (Brainard et al. 2005; Lockley et al. 2006; Vandewalle et al. 2009; Dijket al. 2009; Cajochen et al. 2007). Bright light treatments are dating back to Lewy et al. (1987) who could demonstrate that exposure to bright white light (a mixed spectrum of wavelengths similar to day light) can adjust circadian rhythms and suppress melatonin. The most extensive clinical trials on bright light therapy have focused on seasonal affective disorders suggesting that light can modulate mood in the long term (Wirz-Justice et al. 2004). Today light therapy is used to treat different disorders like sleep disorders, affective disorders, dementia etc. (for a review see Shirani et al. 2009). This chapter will give an overview about the neurobiological basis for light therapy and discuss different mood disorders responsive to light therapy. Additionally, the influence of light on normal brain emotional processing will be discussed.
... It is estimated that the utilization of daylight can reduce the energy consumption on lighting by up to 77% [2]. Daylight predominantly enters buildings via windows, and, to a small extent, via skylights (a mere 3% of American one-floor commercial buildings´floorbuildings´floor areas have integrated skylights [3]). ...
... Light therapy has become a treatment option for various neurological and psychiatric disorders such as sleep disorders, seasonal/non-seasonal affective disorders, and dementia (for reviews see [1,2,3]), because of its short response latency, and the existence of solely minor side effects (usually at the beginning of the treatment, which vanish within days). Light therapy is typically administered daily in the early morning for at least several weeks. ...
... In contrast to above described explicit strategies, emotions can also be influenced with subliminal cues. Temperature control has been shown to mitigate effects of high arousal [11,38] and lighting can also have an influence on affective states [50]. In particular, blue light is shown in related work to have a calming effect [51,52]. ...
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... On the feedback side, we explore the use of ambient light as an emotional feedback modality. Light was shown to have an effect on moods and emotions, e.g., by influencing the circadian system [10]. Ambient lighting in the car has been explored as a means of providing a more comfortable interior, through warning signals of upcoming traffic or to calm down the driver [35]. ...
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Driving is a sensitive task that is strongly affected by the driver’s emotions. Negative emotions, such as anger, can evidently lead to more driving errors. In this work, we introduce a concept of detecting and influencing driver emotions using psycho-physiological sensing for emotion classification and ambient light for feedback. We detect arousal and valence of emotional responses from wearable bio-electric sensors, namely brain-computer interfaces and heart rate sensors. We evaluated our concept in a static driving simulator with a fully equipped car with 12 participants. Before the rides, we elicit negative emotions and evaluate driving performance and physiological data while driving under stressful conditions. We use three ambient lighting conditions (no light, blue, orange). Using a subject-dependent random forests classifier with 40 features collected from physiological data we achieve an average accuracy of \(78.9\%\) for classifying valence and \(68.7\%\) for arousal. Driving performance was enhanced in conditions where ambient lighting was introduced. Both blue and orange light helped drivers to improve lane keeping. We discuss insights from our study and provide design recommendations for designing emotion sensing and feedback systems in the car.
... Light therapy has become a treatment option for various neurological and psychiatric disorders such as sleep disorders, seasonal/non-seasonal affective disorders, and dementia [for reviews see [1][2][3], because of its short response latency, and the existence of solely minor side effects (usually at the beginning of the treatment, which vanish within days). Light therapy is typically administered daily in the early morning for at least several weeks. ...
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Data collection and analysis: Two review authors independently screened references in two stages, extracted outcome data and assessed risk of bias. We used standardised mean differences (SMDs) and 95% confidence intervals (CI) to pool data from different questionnaires and scales assessing the same outcome across different studies. We combined clinically homogeneous studies in a meta-analysis. We used the GRADE system to rate quality of evidence. Main results: The search yielded 2844 references. After screening titles and abstracts, we considered 34 full text articles for inclusion. We scrutinised reports against the eligibility criteria, resulting in the inclusion of five studies (three RCTs and two CBAs) with 282 participants altogether. These studies evaluated four types of comparisons: cool-white light, technically known as high correlated colour temperature (CCT) light versus standard illumination; different proportions of indirect and direct light; individually applied blue-enriched light versus no treatment; and individually applied morning bright light versus afternoon bright light for subsyndromal seasonal affective disorder.We found no studies comparing one level of illuminance versus another.We found two CBA studies (163 participants) comparing high CCT light with standard illumination. By pooling their results via meta-analysis we found that high CCT light may improve alertness (SMD -0.69, 95% CI -1.28 to -0.10; Columbia Jet Lag Scale and the Karolinska Sleepiness Scale) when compared to standard illumination. In one of the two CBA studies with 94 participants there was no difference in positive mood (mean difference (MD) 2.08, 95% CI -0.1 to 4.26) or negative mood (MD -0.45, 95% CI -1.84 to 0.94) assessed using the Positive and Negative Affect Schedule (PANAS) scale. High CCT light may have fewer adverse events than standard lighting (one CBA; 94 participants). Both studies were sponsored by the industry. We graded the quality of evidence as very low.We found no studies comparing light of a particular illuminance and light spectrum or CCT versus another combination of illuminance and light spectrum or CCT.We found no studies comparing daylight versus artificial light.We found one RCT (64 participants) comparing the effects of different proportions of direct and indirect light: 100% direct lighting, 70% direct lighting plus 30% indirect lighting, 30% direct lighting plus 70% indirect lighting and 100% indirect lighting. There was no substantial difference in mood, as assessed by the Beck Depression Inventory, or in adverse events, such as ocular, reading or concentration problems, in the short or medium term. We graded the quality of evidence as low.We found two RCTs comparing individually administered light versus no treatment. According to one RCT with 25 participants, blue-enriched light individually applied for 30 minutes a day may enhance alertness (MD -3.30, 95% CI -6.28 to -0.32; Epworth Sleepiness Scale) and may improve mood (MD -4.8, 95% CI -9.46 to -0.14; Beck Depression Inventory). We graded the quality of evidence as very low. One RCT with 30 participants compared individually applied morning bright light versus afternoon bright light for subsyndromal seasonal affective disorder. There was no substantial difference in alertness levels (MD 7.00, 95% CI -10.18 to 24.18), seasonal affective disorder symptoms (RR 1.60, 95% CI 0.81, 3.20; number of participants presenting with a decrease of at least 50% in SIGH-SAD scores) or frequency of adverse events (RR 0.53, 95% CI 0.26 to 1.07). Among all participants, 57% had a reduction of at least 50% in their SIGH-SAD score. We graded the quality of evidence as low.Publication bias could not be assessed for any of these comparisons. Authors' conclusions: There is very low-quality evidence based on two CBA studies that high CCT light may improve alertness, but not mood, in daytime workers. There is very low-quality evidence based on one CBA study that high CCT light may also cause less irritability, eye discomfort and headache than standard illumination. There is low-quality evidence based on one RCT that different proportions of direct and indirect light in the workplace do not affect alertness or mood. There is very low-quality evidence based on one RCT that individually applied blue-enriched light improves both alertness and mood. There is low-quality evidence based on one RCT that individually administered bright light during the afternoon is as effective as morning exposure for improving alertness and mood in subsyndromal seasonal affective disorder.
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Light therapy is increasingly applied in a variety of sleep medicine and psychiatric conditions including circadian rhythm sleep disorders, seasonal affective disorder, and dementia. This article reviews the neural underpinnings of circadian neurobiology crucial for understanding the influence of light therapy on brain function, common mood and sleep disorders in which light therapy may be effectively used, and applications of light therapy in clinical practice.
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